HYDROLOGICAL IMPACTS OF LAND USE/LAND COVER CHANGE IN THE MAT RIVER BASIN, INDIA

Abstract

Land use-land cover (LULC) changes have significantly affected the Mat River basin, India water cycle over the years. Population development evolving new demands as a result of global growth and varying consumption habits have contributed to a decrease in fresh water supply and distribution over time. In this study, hydrological modeling upper catchment area of Mat River was carried out for the assessment of water availability by using ‘Soil and Water Assessment Tool’ (SWAT) which is a physically based, spatially distributed, a continuous model. SWAT Model was run for a period of 34 years (1986 to 2019 with 1986 & 1987 as warm period). Calibration and validation was done by SWATCUP (SUFI2) using the monthly stream discharges from 1988 to 1996 and 2015 to 2019 respectively. The model is evaluated for performance using Coefficient of Determination (R2), Nash Sutcliffe Efficiency (NSE), Per Cent Bias (PBIAS) and RSR the values of which are 0.72, 0.71, 3.30 and 0.52 respectively during calibration respectively. The calibrated value is used for running SWAT model using LULC of different years (2005, 2010 and 2015). During the study year, the built up area, mixed forest area and orchard coverage increases by 0.428 km2 (17.95%), 13.347 km2 (42.86%) and 0.05 km2 (5.26%) respectively. In the meantime, evergreen forest and agriculture area decreases by 6.57 km2 (6.72%) and 7.29 km2 (45%) respectively. The changes in LULC leads to an increase of average monthly flow during monsoon by 3.92 cumec (0.14%) but decreases during non-monsoon season by 1.20 cumec (0.16%). During this period, the total annual aquifer recharge decreases by 17.25mm while the total water yield increases by a small margin from 1997.96 mm to 1999.49 mm (1.53 mm). The model shows that the average annual rainfall during the study period is 2692.40 mm out of which 1959.57 mm (73%) contributes to stream flow, 515.43 mm goes as evapo-transpiration, 34.16 mm is used for groundwater recharge.